This invention relates to a water-soluble photosensitive composition, a process for forming a pattern using the same and a high-molecular compound. In particular, it relates to a water-soluble photosensitive composition suitable for manufacture of a color cathoderay tube, a process for forming a pattern by using the composition, and a high-molecular compound responding to radiation.
As one example of the conventional pattern forming processes, U.S. Pat. No. 3917794 describes a process for manufacturing a black matrix of a color cathode-ray tube and a photosensitive composition usable for the process. The described process is to form a pattern of areas, which are substantially smaller than irradiated areas, by using a photosensitive composition having a reciprocity law failure characteristic, e.g., a composition comprised of a high-molecular compound such as an acrylamide-diacetone acrylamide copolymer, etc., and a bisazido-type crosslinking reagent.
The above process will be explained in detail hereinbelow. The structure of the black matrix-type color cathode-ray tube is that a phosphor pattern of dots, stripes, or the like, of red, blue and green phosphors is present in the inner surface of a panel, and a nonluminous, light-absorbing material such as carbon, etc., is embedded in spaces which are existing interdot, interstripe, etc. The following explanation is limited to a process for producing a pattern of dots for the explanatory convenience. First, a coating of a photosensitive composition having the above reciprocity law failure characteristic is formed on the inner surface of a color cathode-ray tube faceplate, the phosphor dot-forming positions are exposed through a shadow mask, and the coating is developed to form dots of the photosensitive composition. Carbon is coated thereon, and the dots are removed by a remover liquid together with carbon coated thereon. Holes of black matrix are so formed. Phosphor dots of red, blue and green are formed in the holes successively. Due to the use of a photosensitive composition having the reciprocity law failure characteristic, the areas of the above dots on the photosensitive layer, i.e., the areas of phosphor dots, are substantially smaller than the areas which have been irradiated through the shadow mask. Therefore, in a color cathode-ray tube completed by using the shadow mask, the diameter of electron beam irradiated through the shadow mask is larger than that of the phosphor dot. For this reason, the resultant color cathode-ray tube is clear and excellent in contrast.
However, the above prior art has not taken account of achievement of larger size color cathode-ray tubes, and in manufacturing large-sized color cathode-ray tubes, its problem is that since the surface to be exposed is apart from a light source, the illumination intensity on an exposed surface decreases and the exposure therefore requires a long period of time.